Incidence and cohort prevalence for autism spectrum disorders in the Avalon Peninsula, Newfoundland and Labrador.

BACKGROUND Recent studies have reported increased prevalence for autism spectrum disorders in a number of geographical locations. Our objective was to determine the incidence and 1-year cohort prevalence for autism spectrum disorders in children less than 15 years of age and living in the Avalon Peninsula at the time of diagnosis. METHODS Retrospective and prospective data were obtained from the Janeway Children's Health and Rehabilitation Centre (St. John's), including the identification and specific diagnosis for all children assessed for autism spectrum disorder from 2006 to 2010. Additional clinic data were reviewed to update the data until the end of 2013. RESULTS From 2006 to 2010, 272 children had a diagnosis of autism spectrum disorder, averaging 54 new cases per year. The incidence of new cases increased from 10.1 to 16.7 cases per 10 000 per year from 2006 to 2010. At the end of 2013, the prevalence among children born in 2006 was 1 case of autism spectrum disorder per 46 children or 215.77 per 10 000. INTERPRETATION We found higher rates of autism spectrum disorder than previously reported for this population. The prevalence in this region is also high when compared with other global populations. The high rate of diagnosis supports the need for a provincial autism spectrum disorder registry and further research on autism spectrum disorder within this population.